Propeller



E. P. MARTIN 1,881,365

PROPELLER Filed Nov. 10. 1930 A'rrgnutv Patented -Oct. 4, 1932 UNITED STATES,

PATENT OFFICE EMIL P. MARTIN, OF DETROIT, IIIGHIGAN PROPELLER application filed November 10, 1930. Serial No. 494,713.

provision of a propeller which will be even 1y balanced and will act as a fly wheel or gyroscope, in that use-is made of centrifugal force in the operation of the propeller, while the weight will be thrown forward to the axial center.

Another object of the invention is the provision of a propeller blade of the above character which will grip and cut into the air without slipping, for from approximately three-fourths to one complete revolution.

With the above and other objects in view, the invention further includes'the following novel features and details of construction, to

..u be hereinafter more fully described, illustrated in the accompanying drawing and pointed out in the appended claims.

I In the drawing: I

' Figure 1 is an elevation of a propeller constructed in accordance with the invention.

F igures 2 and 3 peller.

Figure 1 is a section on the line 4-4 of so Figure 1.

Referring to the drawing in detail wherein like characters of reference denote corresponding parts, the reference character indicates the hub of'the propeller from which extends a pair of spiral blades 11 and 12.

While two blades are shown, obviously this number may be increased as desired.

The blades 11 and 12 are of like construction, with the opposite edges 11a and 11a 40 of the blade -11 and the opposite edges 12a and 12a of the blade 12, inwardly curved, and

the end portions of the blades are overlapped i for substantially one-fourth of the circumference of the blades as best shown in Fig- 'ure 1.

taper from their greatest diameters outward to the edges 11a and 12a of'the respective the edges of the blades, the greatest width changes in its form, proportions and minor are edge views of the problades 11, and 12. These beads 13provide "weight at the outer peri heries of the blades so that the blades act a r the manner of a fly wheel, and by tapering the beads toward Tia will be disposed forward of the axial center of the propeller. Due to the construction and relative arrangement of the blades, the propeller will be evenly balanced and the blades will cut into and grip the air from 7 approximately three-fourths to one complete revolution, so that the efliciency of the propeller will be materially increased.

The invention is susceptible of various details of construction and the-right .is here, in reserved to make such changes as properly fall within the scope of the appended claims.

Having described the invention what is claimed is:-

1. In a screw propeller, a hub, a palr of spiral blades carried by the hub with the opposite end portions of one blade overlapping the end portions of the other blade, and a bead extending around the outer edge of each blade said bead tapering toward the ends ,of the blades and having its greatest diameter central of said ends.

2. In a screw propeller, a hub, a palr of spiral blades carried by the hub and having inwardly curved ends, said blades being of like pitch and overlapped for substantially one-fourth of their circumference with the adjacent ends of the blades substantially diametrically arranged and aligned, a bead round in cross section and extending about the peripheral edge of each blade and each bead tapered from its center and terminating in points at the ends of its blade.

In testimony whereof I aflix my s1 aturc. EMIL P. M TIN. 

